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羊水塞栓症の診断フローチャート

羊水が比較的多量に全身性に流入した場合、①心肺虚脱、②NRFS・DIC・弛緩出血、③混合型の羊水塞栓症が発生する可能性が高くなる。子宮血管に羊水が少量流入しても羊水塞栓症が発生することもある。
病態としては、物理的塞栓とアナフィラクトイド反応の2つがあるが、アナフィラクトイド反応によるものが多い。
出典
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1: 著者提供

羊水塞栓症に合併しやすい病態

DICと弛緩出血が7割程度の羊水塞栓症に合併する。
出典
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1: Amniotic fluid embolism: decreased mortality in a population-based study.
著者: W M Gilbert, B Danielsen
雑誌名: Obstet Gynecol. 1999 Jun;93(6):973-7.
Abstract/Text: OBJECTIVE: To examine the risk factors and pregnancy outcomes associated with 53 cases of amniotic fluid embolism that occurred in California during the 2-year period January 1, 1994 to December 31, 1995.
METHODS: Data were obtained from a computerized database that contains linked records from the vital statistics birth certificate and hospital discharge summaries of both mother and newborn. This database covered all singleton deliveries that occurred in 328 civilian acute-care hospitals in California, which represented 98% of all deliveries in California. All cases of amniotic fluid embolism were examined for other pregnancy complications.
RESULTS: There were 1,094,248 deliveries during that 2-year period. Fifty-three singleton gestations had the diagnosis of amniotic fluid embolism, for a population frequency of one per 20,646 deliveries. Fourteen women with amniotic fluid embolism died, for a maternal mortality rate of 26.4%. There were 35 (66%) diagnoses of disseminated intravascular coagulation (DIC), 38 (72%) diagnoses of hemorrhage, and 25 (47%) diagnoses of obstetric shock. Among the 14 women who died, the frequency of DIC (79%) and hemorrhage (71%) was not different compared with that of the survivors (62% and 72%, respectively), but obstetric shock was higher (86%, P = .02) than in survivors (33%). The average maternal length of stay for survivors was 6.5 days (range 3-27 days, median 5 days). The cesarean rate was 60% and the frequency of fetal distress was 49%.
CONCLUSION: In this population-based study of reported cases of amniotic fluid embolism, the maternal mortality rate (26.4%) was significantly less than previously reported and might reflect a more accurate population frequency. In addition, patients who survived and patients who died had similar pregnancy complications, suggesting that amniotic fluid embolism was present in all cases and not limited to those who died.
Obstet Gynecol. 1999 Jun;93(6):973-7.

羊水塞栓症の分類

羊水塞栓症の2大病態は、心肺虚脱症状と弛緩出血・DICである。前者を心肺虚脱型羊水塞栓症、後者の弛緩出血・DICを主体とするもので、子宮組織所見で浮腫、炎症性細胞浸潤を満たすものを子宮型羊水塞栓症という。子宮型羊水塞栓症の早期臨床診断クライテリアを以下に示す。羊水塞栓症のアナフィラクトイド反応の原因としてC1エステラーゼインヒビターの低下が報告されている。
 
子宮型羊水塞栓症の早期臨床診断:
発症時、
  1. ①子宮底長が臍上2指(3~4㎝以上)以上
  1. ②子宮筋層が非常に柔らかい
  1. ③フィブリノゲン値が150mg/dL以下
臨床的羊水塞栓症の診断基準を満たすもので、上記3項目を満たすものを子宮型羊水塞栓症の早期臨床診断とする。
(出典:周産期委員会報告. 日本産科婦人科学会誌. Vol 69(6号) 1467-1470, 2017)
出典
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1: 著者提供

羊水塞栓症によるNRFS発生機序

羊水が母体血中に流入すると子宮・血管の平滑筋攣縮により子宮胎盤循環不全が発生し急激な胎児機能不全となる。一方流入した羊水によりアナフィラクトイド反応が発生し補体、凝固、線溶系、キニン系が活性化しDIC、子宮弛緩症となる。
羊水が母体血中に流入し、子宮血管および子宮平滑筋の過剰な収縮により子宮胎盤循環が阻害され、NRFSとなる。
出典
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1: 著者提供

塞栓タイプの羊水塞栓症とアナフィラキシータイプの羊水塞栓症の肺組織像の差異

a:HE染色。塞栓タイプの羊水塞栓症(肺動脈に塞栓物がみられる)
b:アルシアンブルー染色。アナフィラキシー様反応による羊水塞栓症(肺動脈内に炎症性細胞の集積がみられる)
羊水塞栓症の肺所見には、肺動脈に塞栓が多数みられる塞栓タイプと、炎症性細胞浸潤が多数みられるアナフィラキシー様タイプがある。
出典
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1: 著者提供

羊水塞栓症の子宮組織像

a:HE染色
b:C5a受容体免疫染色
羊水塞栓症の子宮所見は、1)間質の浮腫(巨大な子宮)、2)間質への炎症性細胞浸潤、3)アナフィラキシー様細胞(C5a陽性細胞)の出現が特徴である。
出典
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1: 著者提供

病理解剖の勧めの文書

子宮型羊水塞栓症

子宮型羊水塞栓症のCT
出典
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1: 著者提供

羊水塞栓症のCTG

突然の子宮収縮に引き続きNRFSと突然の母体のショック。
出典
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1: 著者提供

子宮型羊水塞栓症の症例の経過

出典
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羊水塞栓症の診断分類

なお、摘出子宮がある場合、子宮病理所見と臨床所見により子宮型羊水塞栓症と診断できる場合がある。
出典
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1: 著者提供

産科DICスコア

出典
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1: 日本産科婦人科学会ほか編:産科危機的出血への対応指針2022、p3、2022より改編

羊水塞栓症の初期対応

臨床的羊水塞栓症と診断したら、その主たる症状、病態に即した初期対応を行う。低酸素血症が主体なら酸素投与、出血が主病態なら輸液、低血圧なら昇圧剤、サラサラした出血なら抗DIC対策。
出典
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1: 著者提供

DIC治療のポイント

出典
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1: 著者提供

ヘモグロビン/フィブリノゲン比 (H/F ratio)早見表

出典
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1: 著者提供

羊水塞栓症の診断フローチャート

羊水が比較的多量に全身性に流入した場合、①心肺虚脱、②NRFS・DIC・弛緩出血、③混合型の羊水塞栓症が発生する可能性が高くなる。子宮血管に羊水が少量流入しても羊水塞栓症が発生することもある。
病態としては、物理的塞栓とアナフィラクトイド反応の2つがあるが、アナフィラクトイド反応によるものが多い。
出典
img
1: 著者提供

羊水塞栓症に合併しやすい病態

DICと弛緩出血が7割程度の羊水塞栓症に合併する。
出典
imgimg
1: Amniotic fluid embolism: decreased mortality in a population-based study.
著者: W M Gilbert, B Danielsen
雑誌名: Obstet Gynecol. 1999 Jun;93(6):973-7.
Abstract/Text: OBJECTIVE: To examine the risk factors and pregnancy outcomes associated with 53 cases of amniotic fluid embolism that occurred in California during the 2-year period January 1, 1994 to December 31, 1995.
METHODS: Data were obtained from a computerized database that contains linked records from the vital statistics birth certificate and hospital discharge summaries of both mother and newborn. This database covered all singleton deliveries that occurred in 328 civilian acute-care hospitals in California, which represented 98% of all deliveries in California. All cases of amniotic fluid embolism were examined for other pregnancy complications.
RESULTS: There were 1,094,248 deliveries during that 2-year period. Fifty-three singleton gestations had the diagnosis of amniotic fluid embolism, for a population frequency of one per 20,646 deliveries. Fourteen women with amniotic fluid embolism died, for a maternal mortality rate of 26.4%. There were 35 (66%) diagnoses of disseminated intravascular coagulation (DIC), 38 (72%) diagnoses of hemorrhage, and 25 (47%) diagnoses of obstetric shock. Among the 14 women who died, the frequency of DIC (79%) and hemorrhage (71%) was not different compared with that of the survivors (62% and 72%, respectively), but obstetric shock was higher (86%, P = .02) than in survivors (33%). The average maternal length of stay for survivors was 6.5 days (range 3-27 days, median 5 days). The cesarean rate was 60% and the frequency of fetal distress was 49%.
CONCLUSION: In this population-based study of reported cases of amniotic fluid embolism, the maternal mortality rate (26.4%) was significantly less than previously reported and might reflect a more accurate population frequency. In addition, patients who survived and patients who died had similar pregnancy complications, suggesting that amniotic fluid embolism was present in all cases and not limited to those who died.
Obstet Gynecol. 1999 Jun;93(6):973-7.